package 补充.集合框架;

import java.util.HashMap;

public class TestHashMap {
    public static void main(String[] args) {
        HashMap hashMap = new HashMap();
        hashMap.put("stu1","lily");
        hashMap.put("stu2","jack");
        hashMap.put("stu3","Tom");
        hashMap.put("stu4","dook");
        hashMap.put(null,null);
        System.out.println(hashMap.size());//输出集合长度
        System.out.println(hashMap.get("stu1"));//取出键为stu1的值并且输出
        System.out.println(hashMap);

    }
}
